Prior Art
In underground mining, numerous corridors are tunneled into the area to be mined to provide access to the coal or ore to be removed from the mine. Because of the many differing strata of material existing in almost all mined areas, securing the roof area to prevent the shifting and collapse of the strata when left unsupported above the corridors has been a primary problem in the mining activities. Thus, methods of safely securing the roof area are of primary interest, from the standpoint of both safety and expense, to the mining industry.
It has long been the practice to support mine roof areas by drilling anchor bolt holes into the rock formation and securing an anchor bolt therein to provide support to the many strata of rock existing above the corridors. For many years, a molley-type anchoring unit has been inserted into the uppermost portion of the drilled hole with the anchor bolt then inserted into the hole and retained therein by the molley fastener. More recently, it has been the practice to use a curable resin composition with a catalyst to fix anchor bolts into the roof area. The use of a curable resin and catalyst combination to attach the anchor bolts into the rock formation is superior to many prior art methods of attachment because the resin attaches the anchor bolt to the surrounding rock formation along the entire length of the bolt.
Where a curable resin and catalyst is used, it has been advantageous to use quick setting components because of the large quantities which must be installed and because insertion must generally be made overhead. It has also been beneficial to prepackage the resin and the catalyst in a single container having adjacent but separate compartments in which each of the components is housed. In this arrangement, the components are prepackaged in the proper proportions and are mixed within the drill holes by rupture of the container in the holes either immediately before, or by the insertion of the anchor bolts therein. This arrangement has been found especially useful when the surrounding structure does not permit easy access to the location of anchor bolts. Moreover, bringing the components together in this way prevents the premature mixture and thus setting up of the resin and catalyst and thus avoids the waste in time and materials occasioned by other methods of loading the resin and catalyst into the drill holes. Moreover, this arrangement provides a much more reliable attachment of the anchor bolts to the mine wall formations.
Packages heretofore used to compartmentalize a curable resin composition and an appropriate catalyst in an unitary container have suffered from several problems which have made them uneconomical or unreliable. While maintaining some degree of reliability, many prior art compartmented packages are very difficult to manufacture on a continuous basis and are not adaptable to a method of rapid package formation and loading. For example, U.S. Pat. No. Re. 25,869 to Schuermann, et al., issued Oct. 5, 1965, discloses an outer cartridge filled with a curing resin, with a separate capsule containing the catalytic hardener embedded within the filled capsule. Likewise, U.S. Pat. No. 3,302,410, to McLean, issued Oct. 20, 1965, discloses an inner compartment unattached to the outer compartment in which it is embedded. In U.S. Pat. No. 3,737,027, to Ball, issued June 5, 1973, the inner compartment is attached to the outer compartment only at the end thereby requiring that the two be made separately and joined after filling with the appropriate resin or hardener.
Some prior art systems have provided a dual component cartridge in which the two reactive constituents are packed initially in direct contact with no foreign membrane or packaging film of any kind between them. In such systems, the number of usable components are limited and storage and handling of the components is much more critical than in those products where the reactive constituents are separated by a nonreactive membrane. Also, the units have limited shelf life, and catalyst is wasted in forming the polymerized interface. Examples of these prior art systems are found in U.S. Pat. No. 3,731,791 to Fourcade, et al., issued May 8, 1973, and U.S. Pat. No. 3,915,297 to Rausch, issued Oct. 28, 1975.
U.S. Pat. No. 3,861,522 to Llewellyn, et al., issued Jan. 21, 1975, discloses a compartmented package made from a single pliable film material. Dual compartments are formed by forming the film material into a tubular shape and overlapping one edge over the other. The film material is joined to itself at opposite sides of the container. As a result, heat-sealing structure must be provided on both sides of the package as it is being formed.
Other prior art designs, while readily formed and loaded continuously, do not provide a sealing arrangement which assures that the two components will remain separated or within the container during shipping, handling and storage prior to the container's use. U.S. Pat. No. 4,009,778 to Howell, issued Mar. 1, 1977, discloses a dual compartmented package formed by using a single seal to join three plys of material to form the two compartments. In this arrangement, problems are encountered in attempting to seal all three layers of material along one seam. Where the seam is formed by directing a stream of hot gas against the package, temperatures required to adequately seal the innermost layer cause burning of the outermost layer. Where the temperatures are maintained at a level which is optimum to appropriately seal the outermost layer, the temperature is insufficient to adequately seal the innermost layer. Thus, this arrangement has been unsuccessful.